1. Field of the Invention
This invention relates to a finisher, which is connected to an image forming apparatus such as a printer or a copying machine, applying such additional-workings as sorting, binding, creasing, folding, and punching to a recording medium (hereinafter referred to briefly as xe2x80x9csheetxe2x80x9d) such as a recording paper outputted from the image forming apparatus. More particularly, it relates to a finisher with a folding device in which a stopper comes in contact with the leading end of the sheet to form a loop and a pair of rollers nips the loop to fold the sheet.
2. Description of the Prior Art
Recently, various finishers, which apply various additional-workings to a sheet with an image formed surface which are outputted from such image forming devices as printers and copying machines, have been proposed (U.S. patent application Ser. No. 08/821,444). The term xe2x80x9cadditional-workingsxe2x80x9d as used herein means various working processes such as sorting sheets according to the number of copies, filing sheets with staples, folding sheets in two (hereinafter referred to as xe2x80x9cdouble-foldingxe2x80x9d), folding sheets in three or in a cross section like a letter Z (hereinafter referred to as xe2x80x9cZ-foldingxe2x80x9d), and punching sheets for filing.
A finisher, which is illustrated in FIG. 18, has been known as one example of the above finishers. The finisher is provided with a folding mechanism 700. The finisher gives the Z-folding to sheets as follows. First, the folding mechanism 700 receives a sheet with a copied image on the upper surface, which is fed from the right in the diagram. A first folding stopper 704 comes in contact with the sheet to form a loop in the sheet. Then, a pair of folding rollers 701, 702 nips the loop to effect the first folding at a position separated by about one quarter of the size of the sheet in the conveying direction from the leading end of the sheet. Next, the second folding stopper 705 comes in contact with the first fold to form a loop in the sheet. Last, a pair of folding rollers 702, 703 nips the loop to effect the second folding at a roughly central position of the sheet in the conveying direction. Accordingly, the sheet is folded into three parts or in a cross section like a letter Z.
The above conventional folding devices adopt a so-called last page system which copies a plurality of original documents sequentially in reverse order from the last page forward. The last page system, which is provided with the folding mechanism 700 disposed below the finisher as illustrated in the diagram, can change the sheets to be folded in the order of page numbers.
Incidentally, multifunction machines, which work as a printer, facsimile equipment and the like, have been proposed with the popularization of digital copying machines. Such a multifunction machine is utilized for various purposes of copying, printing, facsimile receiving, facsimile transmitting, etc. A user can be confused when all of the functions in a series of documents to be printed do not have the same printing order, such as the order from the first page onward or in reverse order from the last page backward.
The application programs, which are executed by a computer, normally give a printer instructions for printing in the order from page 1 onward. Accordingly, a large number of multifunction machines adopt a so-called first page system in which a printing starts from the first page onward as the common printing order applied to all functions.
The first page system, however, requires a sheet having a copied image in a reverse side be discharged in order to adjust the order of page numbers. A conventional folding device as illustrated in FIG. 18, provided with a reversing mechanism 710a on the front of the folding mechanism 700 as illustrated in FIG. 19 (on condition that a reversing mechanism 710b is not incorporated), folds a sheet with respect to a surface opposite from an image formed surface C as illustrated in FIG. 2A and FIG. 20B and does not fold properly when discharging a sheet having a copied image on a reverse side. A conventional folding device as illustrated in FIG. 18, provided with a reversing mechanism 710b on the front of the discharging unit as illustrated in FIG. 19 (on condition that a reversing mechanism 710a is not incorporated), folds a sheet with respect to the image formed surface C. However, the folding device has to staple a sheaf of temporarily stored sheets as illustrated in FIG. 21A and FIG. 21B, at a stapling position S being the farthest position in a conveying direction of the sheaf when the folding device takes the sheaf out in a direction opposite to a receiving direction of the sheets for temporarily storage. Namely, the folding device has the problem that the stapling is difficult.
In the first page system, it is preferable to store sheets in such a manner as illustrated in FIG. 22A and FIG. 22B for the purpose of fixing the stapling position S in the conveying direction for all the sizes of sheets. It results in shortening the conveying distance of sheets or a sheaf necessary for stapling on the downstream side, securing the accuracy of positioning and reducing the deviation of sheets during the conveyance, for example.
An arrangement as illustrated in FIG. 23, which reverses a sheet P, irrespective of the necessity for a folding, may store sheets in such a manner as illustrated in FIG. 22A and FIG. 22B
In the arrangement, the conveying path is not easily laid out unless the folding mechanism 700 is disposed above the finisher. In general, a finisher stores sheets P temporarily, staples a sheaf of stored sheets and discharges a stapled sheaf into another receiving tray unit. A position of the receiving tray unit which stores a stapled sheaf is preferably lower than a position of the stapler for stapling a sheaf for the purpose of attaining the steady conveyance of the sheaf. A tray, which temporarily receives sheets, must inevitably be disposed on the upper section for the purpose of enlarging a storage capacity for stapled sheaves. A finisher including the folding mechanism 700 disposed on the upper section as well as the tray is of large size as a whole, and loses balance because a component density is high in the upper section.
A finisher with folding rollers having a changed layout, which gives the first folding of the Z-folding to a sheet at the position separated by about three quarters of the size of the sheet from the leading end, namely about one quarter of the size from the trailing end, and not at the position separated by about one quarter of the size of the sheet from the leading end in the conveying direction, can store folded sheets in a desired form. However, the finisher has the problem that an image formed surface of an unfolded sheet faces outward and the order of page numbers is confused.
It is an object of this invention to provide a finisher which adjusts both folded sheets and unfolded sheets in the order of page numbers and staples a sheaf of the sheets easily and accurately, and also utilizes a space efficiently and prevent the size from enlarging.
The present invention accomplishing the object concerns a finisher which comprises a folding device which folds a sheet having an image formed surface, a reversing mechanism which reverses the sheet, and a conveying path for conveying the sheet with bypassing the reversing mechanism, wherein a passage of the sheet through the reversing mechanism is decided on a judgment whether or not the sheet is to be folded. This finisher preparatorily judges whether or not the sheets are to be folded by the folding device and, based on the result of the judgment, actuates the reversing mechanism to reverse the sheet. The finisher according to the so-called first page system can adjust both the folded sheets and the unfolded sheets in the order of page numbers, and only staples the sheets at a position falling on the side of a regulating device disposed in the conveying direction on condition that the sheets are temporarily stored in the tray, and obviates the necessity for changing the stapling position in the conveying direction in response to the size of sheet and the mode of operation.
The finisher reduces the conveying distance for stapling, and obtains the accuracy of the stapling position, and represses the deviation of sheets to only a small extent.
Besides, the folding device is disposed below the finisher. It results in enabling the finisher to utilize space efficiently and prevent the size from enlarging and be in a compact construction. The finisher, when operated in the first page system, inevitably requires a mechanism for reversing sheets. However, the finisher fulfills the requirement simply by incorporating a conveying path for discharging sheets without reversing. Accordingly, the finisher entails neither any notable addition to the size nor any notable increase in cost as compared with the conventional folding device.
This invention also concerns a finisher which comprises a folding device which folds a sheet having an image formed surface and a reversing mechanism which reverses the sheet, wherein the sheet is conveyed to the folding device without passing through the reversing mechanism.
This invention further concerns a method for folding a sheet having an image formed surface, which comprises a step of making a choice between a first mode of folding the sheet and a second mode of not folding the sheet and a step of folding and discharging the sheet in a non-reversed state when the first mode is chosen, and reversing and discharging the sheet without folding when the second mode is chosen.
The objects, characteristics and features of this invention other than those set forth above will become apparent from the following description based on preferred embodiments, which are illustrated in the accompanying drawings.